Runoff Produced by Uniform Rainfall

Q. A small catchment of area $150ha$ received a rainfall of $10.5cm$ in $90minutes$, due to a storm. At the outlet of the catchment, the stream draining the catchment was dry before the storm and experiences a runoff for $10hours$ with an average discharge value of $2.5m^3/sec$.The stream was again dry after the runoff event. The amount of water which was not available to runoff due to combined effect of infiltration, evaporation and transpiration is ____ $m^3$

1. $96\times {10}^4$
2. $67500$
3. $247500$
4. $114\times {10}^4$

Q. A 6 hour storm has 6 cm of rainfall and the resulting runoff was 3 cm. If $\varphi -index$ remains at the same value, which one of the following is the runoff due to 12 cm of rainfall in 9 hours in the catchment?

1. 4.5 cm
2. 6.0 cm
3. 7.5 cm
4. 9.0 cm